1. Field of the Invention
The present invention relates to a bi-directional transfer system and more particularly to a fast acting direct couple bi-directional circuit for transfer of digital data or command levels from a transmitter to a receiver which requires a minimum number of components.
2. Description of the Prior Art
Bi-directional transmission systems which are capable of transferring digital data in two directions on the same line are known. A typical such prior art distribution system is disclosed in U.S. Pat. No. 3,488,634 of the type having a bi-stable device located at a central processor and another bi-stable device located at a console or a piece of external peripheral equipment. The two bi-stable devices are connected by a single bi-directional transmission line system. The bi-stable device at the processor end of the above-mentioned prior art system is embodied in the memory module employing read and write controls. The bi-stable device at the console or input-output device is of the type which usually employs a buffer register. Accordingly, the above-mentioned prior art system requires two write signals or two read signals in order to transfer a set condition from one end of the transmission line to the other.
In the prior art transmission systems it has been customary to use separate transmission lines to transfer data or control information in a single direction and to enable such lines at both the transmitting and receiving end. Prior art bi-directinal transmission line systems employed two sending gates and two receiving gates which were enabled by two read signals or two write signals. Prior art systems which require enabling lines and enabling pulses are relatively slow acting.